scholarly journals Outflows of Very Ionized Gas in the Centers of Seyfert Galaxies: Kinematics and Physical Conditions

2006 ◽  
Vol 653 (2) ◽  
pp. 1098-1114 ◽  
Author(s):  
Alberto Rodriguez‐Ardila ◽  
M. Almudena Prieto ◽  
Sueli Viegas ◽  
Ruth Gruenwald
Keyword(s):  
Seyfert Galaxies ◽  
Ionized Gas ◽  
Physical Conditions ◽  
Galaxies Kinematics

scholarly journals Circumnuclear Emission in Nearby, Non-Interacting Seyfert Galaxies

1989 ◽  
Vol 134 ◽  
pp. 454-456
Author(s):  
Richard W. Pogge
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field ◽  
Seyfert Galaxies ◽  
Ionized Gas ◽  
Physical Conditions

An investigation of the physical conditions present in the circumnuclear regions of 20 nearby, non-interacting Seyfert galaxies is reported. Significant differences are observed between the circumnuclear properties of Seyfert 1s and Seyfert 2s with regards to extended ionized gas. The morphology and ionization of the circumnuclear gas suggests collimation of the nuclear ionizing radiation field; in 4 cases taking the form of distinct conical distributions of ionized gas emanating from the nucleus. Some of these properties are consistent with prevailing “unified” models for AGN. However, it is difficult to reconcile all of the observed differences between Seyfert 1s and 2s with this picture.

scholarly journals Spitzer IRS Observations of Low-Mass Seyfert Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 268-268
Author(s):  
Carol E. Thornton ◽  
Aaron J. Barth ◽  
Luis C. Ho ◽  
Jenny E. Greene
Keyword(s):  
Dust Emission ◽  
Seyfert Galaxies ◽  
Sloan Digital Sky Survey ◽  
Physical Conditions ◽  
Sky Survey ◽  
Low Mass ◽  
Ngc 4395 ◽  
Black Hole Masses

The Sloan Digital Sky Survey has made it possible to identify the first samples of active galaxies with estimated black hole masses below ~ 106M⊙. We have obtained Spitzer IRS low-resolution spectra, covering 5–38 μm, of a sample of 41 Seyfert galaxies with low-mass black holes. Our sample includes SDSS-selected objects from the low-mass Seyfert 1 sample of Greene & Ho (2004) and the low-mass Seyfert 2 sample of Barth et al. (2008), as well as NGC 4395 and POX 52. The goals of this work are to examine the dust emission properties of these objects and investigate the relationship between type 1 and type 2 AGNs at low luminosities and low masses, to search for evidence of star formation, and to use emission-line diagnostics to constrain physical conditions within the narrow-line regions. Here we present preliminary results from this project.

scholarly journals The Herschel Dwarf Galaxy Survey

2019 ◽  
Vol 626 ◽  
pp. A23 ◽  
Author(s):  
D. Cormier ◽  
N. P. Abel ◽  
S. Hony ◽  
V. Lebouteiller ◽  
S. C. Madden ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Spectral Synthesis ◽  
Line Emission ◽  
Ionized Gas ◽  
Star Forming ◽  
Gas Phases ◽  
Physical Conditions ◽  
Radiation Fields ◽  
Low Metallicity

The sensitive infrared telescopes, Spitzer and Herschel, have been used to target low-metallicity star-forming galaxies, allowing us to investigate the properties of their interstellar medium (ISM) in unprecedented detail. Interpretation of the observations in physical terms relies on careful modeling of those properties. We have employed a multiphase approach to model the ISM phases (H II region and photodissociation region) with the spectral synthesis code Cloudy. Our goal is to characterize the physical conditions (gas densities, radiation fields, etc.) in the ISM of the galaxies from the Herschel Dwarf Galaxy Survey. We are particularly interested in correlations between those physical conditions and metallicity or star-formation activity. Other key issues we have addressed are the contribution of different ISM phases to the total line emission, especially of the [C II]157 μm line, and the characterization of the porosity of the ISM. We find that the lower-metallicity galaxies of our sample tend to have higher ionization parameters and galaxies with higher specific star-formation rates have higher gas densities. The [C II] emission arises mainly from PDRs and the contribution from the ionized gas phases is small, typically less than 30% of the observed emission. We also find a correlation – though with scatter – between metallicity and both the PDR covering factor and the fraction of [C II] from the ionized gas. Overall, the low metal abundances appear to be driving most of the changes in the ISM structure and conditions of these galaxies, and not the high specific star-formation rates. These results demonstrate in a quantitative way the increase of ISM porosity at low metallicity. Such porosity may be typical of galaxies in the young Universe.

scholarly journals The MAGNUM survey: different gas properties in the outflowing and disc components in nearby active galaxies with MUSE

2019 ◽  
Vol 622 ◽  
pp. A146 ◽  
Author(s):  
M. Mingozzi ◽  
G. Cresci ◽  
G. Venturi ◽  
A. Marconi ◽  
F. Mannucci ◽  
...  
Keyword(s):  
Radiation Field ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Dust Extinction ◽  
Physical Conditions ◽  
Spatially Resolved ◽  
Line Region ◽  
Central Regions ◽  
Stellar Velocity ◽  
Narrow Line Region

We investigated the interstellar medium (ISM) properties of the disc and outflowing gas in the central regions of nine nearby Seyfert galaxies, all characterised by prominent conical or biconical outflows. These objects are part of the Measuring Active Galactic Nuclei Under MUSE Microscope (MAGNUM) survey, which aims to probe their physical conditions and ionisation mechanism by exploiting the unprecedented sensitivity of the Multi Unit Spectroscopic Explorer (MUSE), combined with its spatial and spectral coverage. Specifically, we studied the different properties of the gas in the disc and in the outflow with spatially and kinematically resolved maps by dividing the strongest emission lines in velocity bins. We associated the core of the lines with the disc, consistent with the stellar velocity, and the redshifted and the blueshifted wings with the outflow. We measured the reddening, density, ionisation parameter, and dominant ionisation source of the emitting gas for both components in each galaxy. We find that the outflowing gas is characterised by higher values of density and ionisation parameter than the disc, which presents a higher dust extinction. Moreover, we distinguish high- and low-ionisation regions across the portion of spatially resolved narrow-line region (NLR) traced by the outflowing gas. The high-ionisation regions characterised by the lowest [N II]/Hα and [S II]/Hα line ratios generally trace the innermost parts along the axis of the emitting cones where the [S III]/[S II] line ratio is enhanced, while the low-ionisation regions follow the cone edges and/or the regions perpendicular to the axis of the outflows, also characterised by a higher [O III] velocity dispersion. A possible scenario to explain these features relies on the presence of two distinct populations of line emitting clouds: one is optically thin to the radiation and is characterised by the highest excitation, while the other is optically thick and is impinged by a filtered, and thus harder, radiation field which generates strong low-excitation lines. The highest values of [N II]/Hα and [S II]/Hα line ratios may be due to shocks and/or a hard filtered radiation field from the active galactic nucleus.

Effects of the hot stellar component on derived physical parameters of the Carina Nebula

1999 ◽  
Vol 193 ◽  
pp. 493-494
Author(s):  
Víctor Robledo-Rella ◽  
Miriam Peña
Keyword(s):  
Physical Parameters ◽  
H Ii Regions ◽  
Ionized Gas ◽  
Physical Conditions ◽  
Stellar Component ◽  
Carina Nebula

Studies of extragalactic (un-resolved) H II regions, usually rely on assumptions about the underlying stellar absorption to estimate the reddening corrections needed to derive physical conditions of the ionized gas and to infer parameters of the ionizing stars (Robledo-Rella & Firmani 1990). We have addressed the problem of estimating quantitatively the effects of the hot star spectra on derived physical (nebular and stellar) parameters of galactic H II regions.

Near infrared spectroscopy of protostars

1981 ◽  
Vol 303 (1480) ◽  
pp. 487-496
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Gas Dynamics ◽  
Near Infrared ◽  
Molecular Gas ◽  
Orion Nebula ◽  
Ionized Gas ◽  
Physical Conditions ◽  
Vibrational Bands ◽  
Optical Wavelengths

Observational study of protostars and their immediate environs has recently become possible as a result of advances in infrared spectroscopy, especially in the near infrared (A = 2—5 pm). Although such stars are totally obscured at optical wavelengths by the enshrouding dust and gas from which they formed, the near infrared spectroscopy has yielded detection of emission lines from both ionized gas and high excitation molecular gas ( T >2000 K) probably within a few astronomical units of several such sources (e.g. the BN object in the Orion nebula). The former lines provide the first constraints on the spectral type and temperature of the protostar; the latter reveal the physical conditions (density and temperature) and gas dynamics in the immediate protostellar nebula. . Data on the BN object covering the CO, 13 CO, and H 2 vibrational bands and the H II lines are presented as an illustration of these techniques.

scholarly journals Origin of the Gas in the Extended Narrow-Line Region of Nearby Seyfert Galaxies: The Case of Mrk 6

2009 ◽  
Vol 5 (S267) ◽  
pp. 327-327
Author(s):  
V. Cracco ◽  
S. Ciroi ◽  
F. Di Mille ◽  
L. Vaona ◽  
P. Rafanelli ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Special Astrophysical Observatory ◽  
Narrow Line ◽  
Physical Processes ◽  
Ionized Gas ◽  
Preliminary Results ◽  
Line Region ◽  
Narrow Line Region ◽  
Open Question

AbstractIonization cones are one of the most important pieces of evidence supporting the AGN unified model (Antonucci & Miller 1985; Urry & Padovani 1995). Until now, the physical processes at work in the cones are not completely understood. A still open question concerns the origin of the gas. To study the origin of the ionized gas, we first selected a sample of nearby (z<0.03) Seyfert galaxies showing extended [O iii] λ5007 emission. We then observed these galaxies with the MultiPupil Fiber Spectrograph (MPFS) at the 6-m telescope of the Special Astrophysical Observatory (Russia). Here we present very preliminary results on the properties of the narrow-line region (NLR) of the intermediate Seyfert galaxy Mrk 6.

Sign in / Sign up

Export Citation Format

Share Document